JP6341378B2 - Power supply device and lighting device - Google Patents

Description

  Embodiments described herein relate generally to a power supply device having a boost chopper circuit that improves the power factor of an input from a DC power supply unit by switching of a switching element, and an illumination device including the power supply device.

  In conventional boost chopper circuits that control semiconductor switching elements to improve power factor, when the input voltage is high or the load is light, the ON width cannot be narrowed down due to the narrowing limit of the ON width of the switching element, and the control limit As a result, the output voltage may increase. In this regard, for example, it is conceivable to use an overvoltage detecting means or the like to stop the oscillation of the switching element when an overvoltage is detected to suppress an increase in output voltage. However, since the overvoltage detected by such an overvoltage detection means is normally set as a threshold value obtained by increasing the regulation voltage by about 10%, the output voltage of the boost chopper circuit is always 10 at light load. The state of operating at an increase of% is not preferable because the load is large for the load side circuit and the output electrolytic capacitor of the step-up chopper circuit.

US Pat. No. 6,946,819

  The problem to be solved by the present invention is to provide a power supply device that can suppress an undesired increase or fluctuation in output voltage when the input voltage of the boost chopper circuit is high or the load is light, and a lighting device including the power supply device. That is.

The power supply apparatus according to the embodiment includes a step-up chopper circuit, a step-down unit, a signal output unit, and a load adjustment unit. The step-up chopper circuit includes a switching element and control means for switching the switching element in accordance with increase / decrease of the current flowing through the switching element, and boosts an input voltage from an external power source by switching the switching element. Step-down transforming means includes a switching element, and a step-down control means for switching the switching element at a predetermined switching frequency, a step-down chopper circuit for supplying to the light source by stepping down the boosted voltage by boost chopper circuit. When the voltage proportional to the input voltage of the step-up chopper circuit is equal to or higher than a predetermined voltage value, the signal output means is equal to or lower than the predetermined dimming level set in advance. A signal is output at least at any time. The load adjusting means operates to increase the load on the step-up chopper circuit by increasing the switching frequency of the switching element by the step-down control means of the step-down means according to the signal output from the signal output means.

  According to the present invention, when the voltage proportional to the input voltage of the step-up chopper circuit becomes equal to or higher than a predetermined voltage value set in advance, and the dimming signal of the light source becomes lower than the predetermined dimming level set in advance. At least in any case, the load adjusting means operates to increase the load on the boost chopper circuit by the signal output from the signal output means, so that the driver suppresses irregular oscillation of the switching element. In addition, it can be expected that an undesired rise or fluctuation in the output voltage of the boost chopper circuit is suppressed.

It is a circuit diagram which shows the power supply device of 1st Embodiment. It is a circuit diagram which shows the power supply device of 2nd Embodiment.

  The configuration of the first embodiment will be described below with reference to the drawings.

  In FIG. 1, reference numeral 10 denotes an illuminating device. The illuminating device 10 includes a power supply device 11 and a light source 12 that is a light emitting element such as an LED as a load.

  That is, the power supply device 11 is for a lighting device that turns on the light source 12. The power supply device 11 includes a power supply unit 15 connected to a commercial AC power source e that is an external power supply (AC power supply unit), and the power supply. A step-up chopper circuit 16 that outputs a DC voltage to the unit 15 and a step-down chopper circuit 17 that is a step-down means that is electrically connected to the step-up chopper circuit 16 and supplies power to the light source 12 are provided.

  The power supply unit 15 is an input capacitor of a step-up chopper circuit 16 such as a noise filter circuit (not shown) and a rectifying element 22 connected to the noise filter circuit and an electrolytic capacitor that is a smoothing element that smoothes the output from the rectifying element 22. And a smoothing capacitor C1.

  The noise filter circuit is a known line filter configured by, for example, a fuse, a capacitor, a common mode choke, and a capacitor.

  The rectifying element 22 is a full-wave rectifying element such as a bridge diode connected to the output side of the noise filter circuit.

  The step-up chopper circuit 16 is a current critical power factor correction circuit that converts the output voltage from the power supply unit 15 into a desired voltage, and converts the AC power of an AC sine wave or AC rectangular wave into DC. In the boost chopper circuit 16, a series circuit of an inductor L1 that is a boosting transformer (chopper choke) and a reverse blocking diode D1 is connected to the power supply unit 15, and the inductor L1 and the diode D1 are connected to each other. A switching element Q1 (for boosting chopping) such as a P-channel type MOSFET is connected to the connection point with the anode, and a smoothing capacitor C2 that is an output capacitor such as an electrolytic capacitor is connected to the cathode side of the diode D1 that is the output side. In addition, a driver 24 (for a boost chopper) is provided as control means for switching control of the switching element Q1.

  In the inductor L1, the primary winding L1a is connected between the output side of the rectifying element 22 and the anode of the diode D1, and the secondary winding (auxiliary winding) L1b is connected to the driver 24.

  In the switching element Q1, the drain terminal is connected to the connection point between the inductor L1 (primary winding L1a) and the anode of the diode D1, and the source terminal on the output side is connected to the ground potential via the current detection resistor R1. It is connected to the. Further, the gate terminal which is the control terminal of the switching element Q1 is connected to the driver 24.

  The driver 24 includes an input voltage detection unit 25 that detects the input voltage Vin of the boost chopper circuit 16, an output voltage detection unit 26 that detects the output voltage Vout of the boost chopper circuit 16, and a current (source current) I flowing through the switching element Q1. The current detection unit 27 to detect, the current flowing through the inductor L1, and the load adjustment means 28 are electrically connected. The driver 24 determines the switching element Q1 based on the input voltage Vin detected by the input voltage detector 25, the output voltage Vout detected by the output voltage detector 26, and the current I detected by the current detector 27. Is a control IC that controls the ON width (duty) of the switching element Q1 (sets the ON time and OFF time), and at least the current I flowing through the switching element Q1 increases (decreases). Sometimes the ON width of the switching element Q1 is increased (decreased). That is, the driver 24 switches the switching element Q1 according to the increase / decrease of the current I.

  The input voltage detection unit 25 is connected between the power supply unit 15 (rectifier element 22) and the boost chopper circuit 16 (smoothing capacitor C1). The input voltage detection unit 25 is configured by connecting a plurality of (input voltage) detection resistors R2 and R3 in series, and corresponds to the input voltage Vin of the boost chopper circuit 16 by dividing the detection resistors R2 and R3 (proportional ) To detect the input voltage Vin of the boost chopper circuit 16 (the output voltage of the power supply unit 15). A connection point (middle point) between the detection resistors R2 and R3 is connected to the driver 24.

  The output voltage detection unit 26 is connected between the step-up chopper circuit 16 (smoothing capacitor C2) and the step-down chopper circuit 17. The output voltage detection unit 26 is configured by connecting a plurality of (output voltage) detection resistors R4 and R5 in series, and corresponds to the output voltage Vout of the boost chopper circuit 16 by dividing the detection resistors R4 and R5 (proportional) ) To detect the output voltage Vout of the step-up chopper circuit 16 (the input voltage of the step-down chopper circuit 17). The connection point (midpoint) of the detection resistors R4 and R5 is connected to the driver 24.

  In addition to the resistor R1, the current detection unit 27 includes a resistor R6 that is a detection element connected between a connection point between the resistor R1 and the source terminal of the switching element Q1 and the driver 24, and a capacitor that grounds the resistor R6. C3 is provided, and a current proportional to the current I flowing through the switching element Q1 is detected as a voltage.

  The load adjusting means 28 includes a series circuit 29 of a dummy resistor R7, which is a resistance as an impedance element, a switching element Q2 such as a P-channel type MOSFET, and the driver 24 for switching the switching element Q2. .

  The series circuit 29 is connected between the step-up chopper circuit 16 (smoothing capacitor C2) and the step-down chopper circuit 17 (output voltage detection unit 26), and is parallel to the step-down chopper circuit 17 with respect to the step-up chopper circuit 16, that is, a smoothing capacitor. Connected across C2. The switching element Q2 of the series circuit 29 has a drain terminal connected to the dummy resistor R7, a source terminal grounded, and a gate terminal that is a control terminal connected to the driver 24. The driver 24 is connected to a microcomputer 30 as signal output means.

  The microcomputer 30 is connected to the connection point (midpoint) of the detection resistors R2 and R3 of the input voltage detection unit 25 and the dimming signal receiving means 35, and is grounded.

  Here, the dimming signal receiving means 35 includes a rectifying element 38 connected to a signal source 37 to which a dimming signal which is a PWM signal is input manually, for example, and a photocoupler 39 connected to the rectifying element 38. And a pull-up resistor R8 connected to the photocoupler 39. The rectifier element 38 is a full-wave rectifier element such as a bridge diode that rectifies a dimming signal that is a PWM signal and supplies the rectified signal to the photocoupler 39. The photocoupler 39 includes a photodiode PD and a phototransistor PT, and the photodiode PD connected to the rectifying element 38 is turned on in response to the dimming signal rectified by the rectifying element 38. The phototransistor PT is a switching element that is turned on and off in accordance with the light emission of the photodiode PD, the emitter terminal is grounded, and the collector terminal is connected to a predetermined voltage source V via the pull-up resistor R8. In addition, it is connected to the microcomputer 30. Therefore, the dimming signal receiving means 35 turns on the phototransistor PT when the dimming signal is at a high level and outputs a low level signal, and turns off the phototransistor PT when the dimming signal is at a low level. A level signal is output.

  Then, the microcomputer 30 determines that the dimming signal received from the signal source 37 by the dimming signal receiving means 35 is equal to or lower than a predetermined dimming level set in advance, that is, the light source 12 is set to be higher than a predetermined dimming depth set in advance. When a dimming signal instructing dimming is received by the dimming signal receiving means 35 and a signal corresponding to the dimming signal is input from the dimming signal receiving means 35 (photocoupler 39), the input voltage When at least one of the case where the input voltage Vin detected by the detection unit 25 is equal to or higher than a predetermined voltage set in advance, a predetermined signal is output to the driver 24, and the predetermined signal output by the microcomputer 30 is output. Based on this, the driver 24 outputs a high level signal to the gate terminal of the switching element Q2 to turn on the switching element Q2.

  In the step-down chopper circuit 17, a series circuit of a switching element Q3 (for step-down chopping) such as a P-channel MOSFET and a diode D2 is connected to both ends of the smoothing capacitor C2. Further, the inductor L2 is connected to the cathode of the diode D2, the anode of the diode D2 is grounded, and the light source 12 is connected in parallel to the diode D2. A gate terminal which is a control terminal of the switching element Q3 is connected to a driver 41 (for a step-down chopper) which is a control IC as a step-down control means for setting an ON time and an OFF time of the switching element Q3. The driver 41 turns on and off the switching element Q3 at a predetermined switching frequency, and controls the ON width (duty) of the switching element Q3 according to, for example, the dimming signal received by the dimming signal receiving unit 35 (on time and By setting the off time), the light source 12 is controlled to flow a predetermined constant current.

  Next, the operation of the first embodiment will be described.

  When the power supply device 11 is activated, the commercial AC power source e is rectified by the rectifying element 22, smoothed by the smoothing capacitor C1, and input to the step-up chopper circuit 16. In the step-up chopper circuit 16, the switching element Q1 is switched by the driver 24, the power supply voltage rectified and smoothed by the rectifying element 22 and the smoothing capacitor C1 is boosted to a predetermined power supply voltage, and the voltage smoothed by the smoothing capacitor C2 is stepped down. Supply to the chopper circuit 17. In the step-down chopper circuit 17, the switching element Q3 is switched by the driver 41, the output voltage Vout of the step-up chopper circuit 16 is stepped down to a predetermined voltage, and supplied to the light source 12, whereby the light source 12 is turned on.

  The driver 24 detects the timing at which the voltage proportional to the induced voltage of the primary winding L1a induced in the secondary winding L1b of the inductor L1 starts to drop due to the discharge of all the energy stored in the inductor L1, thereby When the critical point of the current I flowing through L1 is detected by the current detection unit 27 and when it is detected that the current I of the inductor L1 has become zero, the switching element Q1 is turned on, whereby the output voltage of the boost chopper circuit 16 Feedback control is performed so that Vout approaches the target value.

  Further, in the driver 41, for example, according to the dimming signal received from the signal source 37 by the dimming signal receiving means 35, the on-time and the off-time (duty) of the switching element Q3 are set to flow to the light source 12. The light source 12 is dimmed by feedback control so that the constant current approaches the target value.

  Here, when the power supply voltage (input voltage Vin) is high and the dimming level of the light source 12 is lower than a predetermined level (the dimming depth is higher than a predetermined level), or when the load is light, the current I flowing through the switching element Q1 decreases to a predetermined value or lower. In other words, the switching range of the switching element Q1 by the driver 24 becomes irregular due to the control range in which the switching element Q1 needs to be equal to or smaller than the minimum on-width, and the output voltage Vout of the step-up chopper circuit 16 increases undesirably or fluctuate. Therefore, in this embodiment, the voltage proportional to the input voltage Vin of the boost chopper circuit 16 detected by the input voltage detection unit 25 is equal to or higher than a predetermined voltage (the input voltage Vin of the boost chopper circuit 16 is set in advance). And a high level signal is output from the microcomputer 30 to the gate terminal of the switching element Q2, and the switching element Q2 is turned on. When the switching element Q2 is turned on, the dummy resistor R7 is turned on. Power loss occurs, that is, the load adjusting means 28 operates to increase the load on the boost chopper circuit 16, so that the driver 24 suppresses irregular oscillation of the switching element Q1, and the minimum ON in a wider power supply phase. In order to perform switching control regularly or substantially regularly by the width, the output voltage Vout of the boost chopper circuit 16 rises undesirably or Can suppress fluctuations.

  Similarly, when the dimming level of the light source 12 is equal to or lower than the predetermined level (the dimming depth is equal to or higher than the predetermined level), that is, the dimming signal for dimming the light source 12 is a signal that indicates the dimming level or lower. Since the output voltage Vout of the chopper circuit 16 is likely to rise or fluctuate undesirably, when this dimming signal is received by the dimming signal receiving means 35, a high level signal is sent from the microcomputer 30 to the gate terminal of the switching element Q2. Since this switching element Q2 is output and the switching element Q2 is turned on, the power loss due to the dummy resistor R7 occurs when the switching element Q2 is turned on, that is, the load adjusting means 28 operates so as to increase the load on the boost chopper circuit 16. 24 suppresses irregular oscillation of the switching element Q1, and performs switching control regularly or substantially regularly with the minimum ON width in a wider power supply phase. , It is possible to suppress the output voltage Vout of the step-up chopper circuit 16 rises or fluctuates undesirably.

  When the output voltage Vout is controlled to a predetermined output voltage, a predetermined signal is output from the microcomputer 30 to the driver 24, and based on the predetermined signal output from the microcomputer 30, the driver 24 is driven to the gate terminal of the switching element Q2. The level signal is output and the switching element Q2 is turned off.

  The load adjusting means 28 includes a dummy resistor R7 and a series circuit 29 of the switching element Q2, a driver 24 of the boost chopper circuit 16, and a microcomputer that outputs a predetermined signal for the driver 24 to switch on and off the switching element Q2. Thus, the load adjusting means 28 can be formed easily and inexpensively.

  Next, a second embodiment will be described with reference to FIG. In addition, about the structure and effect | action similar to the said 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  In the second embodiment, load adjusting means 43 including a step-down chopper circuit 17 and a microcomputer 30 is provided in place of the load adjusting means 28 of the first embodiment.

  Here, the driver 41 of the step-down chopper circuit 17 is connected to the comparator 44 and the microcomputer 30. The comparator 44 has a non-inverting input terminal connected to the reference voltage Vth, and an inverting input terminal connected to a connection point between the current detection resistor R9 and the light source 12 for detecting the current flowing through the light source 12 as a voltage, and output. The terminal is connected to the driver 41. Then, the comparator 44 outputs the result of comparing the reference voltage Vth and the voltage corresponding to the current flowing through the light source 12 detected via the resistor R9 to the driver 41, and the driver 41 switches the switching element according to this comparison result. By controlling the ON width (duty) of Q3, the current flowing through the light source 12 becomes a predetermined constant current.

  Then, the microcomputer 30 adjusts the dimming signal received from the signal source 37 by the dimming signal receiving means 35 to a predetermined dimming level or lower, that is, the light source 12 is adjusted at a predetermined dimming depth. When the dimming signal receiving means 35 receives a dimming signal instructing to illuminate and a signal corresponding to the dimming signal is input from the dimming signal receiving means 35 (photocoupler 39), and input voltage detection For example, a high level signal is output to the driver 41 in at least one of the case where the input voltage Vin detected by the unit 25 is equal to or higher than a predetermined voltage set in advance.

  For this reason, when the power supply device 11 is in operation, when the power supply voltage (input voltage Vin) is high and the dimming level of the light source 12 is below a predetermined level (the dimming depth is above a predetermined level) or light load, the current that flows through the switching element Q1 When I decreases below a predetermined value, that is, the control range requires a switching element Q1 that is less than the minimum ON width, switching of the switching element Q1 by the driver 24 becomes irregular, and the output voltage of the boost chopper circuit 16 Vout rises or fluctuates undesirably, for example, a voltage proportional to the input voltage Vin of the boost chopper circuit 16 detected by the input voltage detection unit 25 becomes equal to or higher than a predetermined voltage (the input voltage of the boost chopper circuit 16 When Vin becomes a predetermined voltage (for example, 242 V or higher) set in advance, a high level signal is output from the microcomputer 30 to the driver 41 of the step-down chopper circuit 17, and the driver 41 is switched on. The switching frequency of the chucking element Q3 is increased (for example, increased from 50 kHz to 80 kHz). As a result, the power loss in the step-down chopper circuit 17 increases, that is, the load adjusting means 43 operates so as to increase the load on the step-up chopper circuit 16, so that the driver 24 suppresses irregular oscillation of the switching element Q1. Since switching control is performed regularly or substantially regularly with a minimum on-width in a wider power supply phase, it is possible to suppress the output voltage Vout of the step-up chopper circuit 16 from rising or fluctuating undesirably.

  Similarly, when the dimming level of the light source 12 is equal to or lower than the predetermined level (the dimming depth is equal to or higher than the predetermined level), that is, the dimming signal for dimming the light source 12 is a signal that indicates the dimming level or lower. Since the output voltage Vout of the chopper circuit 16 easily rises or fluctuates undesirably, when this dimming signal is received by the dimming signal receiving means 35, a high level signal is sent from the microcomputer 30 to the driver 41 of the step-down chopper circuit 17. The driver 41 increases the switching frequency of the switching element Q3 (for example, increases from 50 kHz to 80 kHz). As a result, the power loss in the step-down chopper circuit 17 increases, that is, the load adjusting means 43 operates so as to increase the load on the step-up chopper circuit 16, so that the driver 24 suppresses irregular oscillation of the switching element Q1. Since switching control is performed regularly or substantially regularly with a minimum on-width in a wider power supply phase, it is possible to suppress the output voltage Vout of the step-up chopper circuit 16 from rising or fluctuating undesirably.

  When the output voltage Vout is controlled to a predetermined output voltage, a low level signal is output from the microcomputer 30 to the driver 41, and the switching frequency of the driver 41 is restored.

  Further, since the load adjusting means 43 is constituted by the step-down chopper circuit 17 and the microcomputer 30 that outputs a signal for changing the switching frequency by the driver 41 of the switching element Q3 of the step-down chopper circuit 17, the minimum power consumption is required. The load on the boost chopper circuit 16 can be increased.

  In each of the above embodiments, the microcomputer 30 has a voltage proportional to the input voltage Vin of the step-up chopper circuit 16 detected by the input voltage detection unit 25 equal to or higher than a predetermined voltage and a dimming signal receiving unit. When the dimming signal received by 35 is a signal indicating the dimming level or less, a high level signal may be output from the microcomputer 30 to the gate terminal of the switching element Q2 of the load adjusting means 28.

  Further, the step-up chopper circuit 16 may be a current continuous type or a current discontinuous type other than the current critical type.

  Furthermore, when the power supply device 11 supports a plurality of light sources 12 having different load voltages, it is possible to more effectively suppress the output voltage Vout of the boost chopper circuit 16 from being undesirably increased or fluctuated.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

10 Lighting equipment
11 Power supply
12 Light source
16 Boost chopper circuit
17 Step-down chopper circuit as step-down means
24 Driver as control means
43 load adjustment hand stage
30 Microcomputer as signal output means
41 Driver I current as step-down control means
Q1, Q3 switching element

Claims (2)

A step-up chopper circuit that includes a switching element and a control unit that switches the switching element in accordance with an increase / decrease in current flowing through the switching element, and that boosts an input voltage from an external power source by switching the switching element;
A step-down means comprising a switching element and step-down control means for switching the switching element at a predetermined switching frequency, and a step-down chopper circuit that steps down a voltage boosted by the step-up chopper circuit and supplies the stepped-down chopper circuit to the light source;
At least one of when the voltage proportional to the input voltage of the step-up chopper circuit becomes equal to or higher than a predetermined voltage value set in advance and when the dimming signal of the light source becomes lower than a predetermined dimming level set in advance. Signal output means for outputting a signal at any time;
Load adjusting means that operates to increase the load on the step-up chopper circuit by increasing the switching frequency of the switching element by the step-down control means of the step-down means according to the signal output by the signal output means;
Power supply, characterized in that comprises a. With a light source;
A power supply device according to claim 1 wherein the feed to the light source;
An illumination device comprising:

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